scripts/sortextable.c

   1 /*
   2  * sortextable.c: Sort the kernel's exception table
   3  *
   4  * Copyright 2011 - 2012 Cavium, Inc.
   5  *
   6  * Based on code taken from recortmcount.c which is:
   7  *
   8  * Copyright 2009 John F. Reiser <jreiser@BitWagon.com>.  All rights reserved.
   9  * Licensed under the GNU General Public License, version 2 (GPLv2).
  10  *
  11  * Restructured to fit Linux format, as well as other updates:
  12  *  Copyright 2010 Steven Rostedt <srostedt@redhat.com>, Red Hat Inc.
  13  */
  14
  15 /*
  16  * Strategy: alter the vmlinux file in-place.
  17  */
  18
  19 #include <sys/types.h>
  20 #include <sys/mman.h>
  21 #include <sys/stat.h>
  22 #include <getopt.h>
  23 #include <elf.h>
  24 #include <fcntl.h>
  25 #include <setjmp.h>
  26 #include <stdio.h>
  27 #include <stdlib.h>
  28 #include <string.h>
  29 #include <unistd.h>
  30
  31 #include <tools/be_byteshift.h>
  32 #include <tools/le_byteshift.h>
  33
  34 #ifndef EM_ARCOMPACT
  35 #define EM_ARCOMPACT    93
  36 #endif
  37
  38 #ifndef EM_XTENSA
  39 #define EM_XTENSA       94
  40 #endif
  41
  42 #ifndef EM_AARCH64
  43 #define EM_AARCH64      183
  44 #endif
  45
  46 #ifndef EM_MICROBLAZE
  47 #define EM_MICROBLAZE   189
  48 #endif
  49
  50 #ifndef EM_ARCV2
  51 #define EM_ARCV2        195
  52 #endif
  53
  54 static int fd_map;      /* File descriptor for file being modified. */
  55 static int mmap_failed; /* Boolean flag. */
  56 static void *ehdr_curr; /* current ElfXX_Ehdr *  for resource cleanup */
  57 static struct stat sb;  /* Remember .st_size, etc. */
  58 static jmp_buf jmpenv;  /* setjmp/longjmp per-file error escape */
  59
  60 /* setjmp() return values */
  61 enum {
  62         SJ_SETJMP = 0,  /* hardwired first return */
  63         SJ_FAIL,
  64         SJ_SUCCEED
  65 };
  66
  67 /* Per-file resource cleanup when multiple files. */
  68 static void
  69 cleanup(void)
  70 {
  71         if (!mmap_failed)
  72                 munmap(ehdr_curr, sb.st_size);
  73         close(fd_map);
  74 }
  75
  76 static void __attribute__((noreturn))
  77 fail_file(void)
  78 {
  79         cleanup();
  80         longjmp(jmpenv, SJ_FAIL);
  81 }
  82
  83 /*
  84  * Get the whole file as a programming convenience in order to avoid
  85  * malloc+lseek+read+free of many pieces.  If successful, then mmap
  86  * avoids copying unused pieces; else just read the whole file.
  87  * Open for both read and write.
  88  */
  89 static void *mmap_file(char const *fname)
  90 {
  91         void *addr;
  92
  93         fd_map = open(fname, O_RDWR);
  94         if (fd_map < 0 || fstat(fd_map, &sb) < 0) {
  95                 perror(fname);
  96                 fail_file();
  97         }
  98         if (!S_ISREG(sb.st_mode)) {
  99                 fprintf(stderr, "not a regular file: %s\n", fname);
 100                 fail_file();
 101         }
 102         addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED,
 103                     fd_map, 0);
 104         if (addr == MAP_FAILED) {
 105                 mmap_failed = 1;
 106                 fprintf(stderr, "Could not mmap file: %s\n", fname);
 107                 fail_file();
 108         }
 109         return addr;
 110 }
 111
 112 static uint64_t r8be(const uint64_t *x)
 113 {
 114         return get_unaligned_be64(x);
 115 }
 116 static uint32_t rbe(const uint32_t *x)
 117 {
 118         return get_unaligned_be32(x);
 119 }
 120 static uint16_t r2be(const uint16_t *x)
 121 {
 122         return get_unaligned_be16(x);
 123 }
 124 static uint64_t r8le(const uint64_t *x)
 125 {
 126         return get_unaligned_le64(x);
 127 }
 128 static uint32_t rle(const uint32_t *x)
 129 {
 130         return get_unaligned_le32(x);
 131 }
 132 static uint16_t r2le(const uint16_t *x)
 133 {
 134         return get_unaligned_le16(x);
 135 }
 136
 137 static void w8be(uint64_t val, uint64_t *x)
 138 {
 139         put_unaligned_be64(val, x);
 140 }
 141 static void wbe(uint32_t val, uint32_t *x)
 142 {
 143         put_unaligned_be32(val, x);
 144 }
 145 static void w2be(uint16_t val, uint16_t *x)
 146 {
 147         put_unaligned_be16(val, x);
 148 }
 149 static void w8le(uint64_t val, uint64_t *x)
 150 {
 151         put_unaligned_le64(val, x);
 152 }
 153 static void wle(uint32_t val, uint32_t *x)
 154 {
 155         put_unaligned_le32(val, x);
 156 }
 157 static void w2le(uint16_t val, uint16_t *x)
 158 {
 159         put_unaligned_le16(val, x);
 160 }
 161
 162 static uint64_t (*r8)(const uint64_t *);
 163 static uint32_t (*r)(const uint32_t *);
 164 static uint16_t (*r2)(const uint16_t *);
 165 static void (*w8)(uint64_t, uint64_t *);
 166 static void (*w)(uint32_t, uint32_t *);
 167 static void (*w2)(uint16_t, uint16_t *);
 168
 169 typedef void (*table_sort_t)(char *, int);
 170
 171 /*
 172  * Move reserved section indices SHN_LORESERVE..SHN_HIRESERVE out of
 173  * the way to -256..-1, to avoid conflicting with real section
 174  * indices.
 175  */
 176 #define SPECIAL(i) ((i) - (SHN_HIRESERVE + 1))
 177
 178 static inline int is_shndx_special(unsigned int i)
 179 {
 180         return i != SHN_XINDEX && i >= SHN_LORESERVE && i <= SHN_HIRESERVE;
 181 }
 182
 183 /* Accessor for sym->st_shndx, hides ugliness of "64k sections" */
 184 static inline unsigned int get_secindex(unsigned int shndx,
 185                                         unsigned int sym_offs,
 186                                         const Elf32_Word *symtab_shndx_start)
 187 {
 188         if (is_shndx_special(shndx))
 189                 return SPECIAL(shndx);
 190         if (shndx != SHN_XINDEX)
 191                 return shndx;
 192         return r(&symtab_shndx_start[sym_offs]);
 193 }
 194
 195 /* 32 bit and 64 bit are very similar */
 196 #include "sortextable.h"
 197 #define SORTEXTABLE_64
 198 #include "sortextable.h"
 199
 200 static int compare_relative_table(const void *a, const void *b)
 201 {
 202         int32_t av = (int32_t)r(a);
 203         int32_t bv = (int32_t)r(b);
 204
 205         if (av < bv)
 206                 return -1;
 207         if (av > bv)
 208                 return 1;
 209         return 0;
 210 }
 211
 212 static void sort_relative_table(char *extab_image, int image_size)
 213 {
 214         int i;
 215
 216         /*
 217          * Do the same thing the runtime sort does, first normalize to
 218          * being relative to the start of the section.
 219          */
 220         i = 0;
 221         while (i < image_size) {
 222                 uint32_t *loc = (uint32_t *)(extab_image + i);
 223                 w(r(loc) + i, loc);
 224                 i += 4;
 225         }
 226
 227         qsort(extab_image, image_size / 8, 8, compare_relative_table);
 228
 229         /* Now denormalize. */
 230         i = 0;
 231         while (i < image_size) {
 232                 uint32_t *loc = (uint32_t *)(extab_image + i);
 233                 w(r(loc) - i, loc);
 234                 i += 4;
 235         }
 236 }
 237
 238 static void
 239 do_file(char const *const fname)
 240 {
 241         table_sort_t custom_sort;
 242         Elf32_Ehdr *ehdr = mmap_file(fname);
 243
 244         ehdr_curr = ehdr;
 245         switch (ehdr->e_ident[EI_DATA]) {
 246         default:
 247                 fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
 248                         ehdr->e_ident[EI_DATA], fname);
 249                 fail_file();
 250                 break;
 251         case ELFDATA2LSB:
 252                 r = rle;
 253                 r2 = r2le;
 254                 r8 = r8le;
 255                 w = wle;
 256                 w2 = w2le;
 257                 w8 = w8le;
 258                 break;
 259         case ELFDATA2MSB:
 260                 r = rbe;
 261                 r2 = r2be;
 262                 r8 = r8be;
 263                 w = wbe;
 264                 w2 = w2be;
 265                 w8 = w8be;
 266                 break;
 267         }  /* end switch */
 268         if (memcmp(ELFMAG, ehdr->e_ident, SELFMAG) != 0
 269         ||  r2(&ehdr->e_type) != ET_EXEC
 270         ||  ehdr->e_ident[EI_VERSION] != EV_CURRENT) {
 271                 fprintf(stderr, "unrecognized ET_EXEC file %s\n", fname);
 272                 fail_file();
 273         }
 274
 275         custom_sort = NULL;
 276         switch (r2(&ehdr->e_machine)) {
 277         default:
 278                 fprintf(stderr, "unrecognized e_machine %d %s\n",
 279                         r2(&ehdr->e_machine), fname);
 280                 fail_file();
 281                 break;
 282         case EM_386:
 283         case EM_X86_64:
 284         case EM_S390:
 285                 custom_sort = sort_relative_table;
 286                 break;
 287         case EM_ARCOMPACT:
 288         case EM_ARCV2:
 289         case EM_ARM:
 290         case EM_AARCH64:
 291         case EM_MICROBLAZE:
 292         case EM_MIPS:
 293         case EM_XTENSA:
 294                 break;
 295         }  /* end switch */
 296
 297         switch (ehdr->e_ident[EI_CLASS]) {
 298         default:
 299                 fprintf(stderr, "unrecognized ELF class %d %s\n",
 300                         ehdr->e_ident[EI_CLASS], fname);
 301                 fail_file();
 302                 break;
 303         case ELFCLASS32:
 304                 if (r2(&ehdr->e_ehsize) != sizeof(Elf32_Ehdr)
 305                 ||  r2(&ehdr->e_shentsize) != sizeof(Elf32_Shdr)) {
 306                         fprintf(stderr,
 307                                 "unrecognized ET_EXEC file: %s\n", fname);
 308                         fail_file();
 309                 }
 310                 do32(ehdr, fname, custom_sort);
 311                 break;
 312         case ELFCLASS64: {
 313                 Elf64_Ehdr *const ghdr = (Elf64_Ehdr *)ehdr;
 314                 if (r2(&ghdr->e_ehsize) != sizeof(Elf64_Ehdr)
 315                 ||  r2(&ghdr->e_shentsize) != sizeof(Elf64_Shdr)) {
 316                         fprintf(stderr,
 317                                 "unrecognized ET_EXEC file: %s\n", fname);
 318                         fail_file();
 319                 }
 320                 do64(ghdr, fname, custom_sort);
 321                 break;
 322         }
 323         }  /* end switch */
 324
 325         cleanup();
 326 }
 327
 328 int
 329 main(int argc, char *argv[])
 330 {
 331         int n_error = 0;  /* gcc-4.3.0 false positive complaint */
 332         int i;
 333
 334         if (argc < 2) {
 335                 fprintf(stderr, "usage: sortextable vmlinux...\n");
 336                 return 0;
 337         }
 338
 339         /* Process each file in turn, allowing deep failure. */
 340         for (i = 1; i < argc; i++) {
 341                 char *file = argv[i];
 342                 int const sjval = setjmp(jmpenv);
 343
 344                 switch (sjval) {
 345                 default:
 346                         fprintf(stderr, "internal error: %s\n", file);
 347                         exit(1);
 348                         break;
 349                 case SJ_SETJMP:    /* normal sequence */
 350                         /* Avoid problems if early cleanup() */
 351                         fd_map = -1;
 352                         ehdr_curr = NULL;
 353                         mmap_failed = 1;
 354                         do_file(file);
 355                         break;
 356                 case SJ_FAIL:    /* error in do_file or below */
 357                         ++n_error;
 358                         break;
 359                 case SJ_SUCCEED:    /* premature success */
 360                         /* do nothing */
 361                         break;
 362                 }  /* end switch */
 363         }
 364         return !!n_error;
 365 }